[MPlayer-DOCS] [PATCH] merge Rich's cropping and scaling tips into mencoder.xml

[The Wanderer]

Only one actual improvement to suggest, but a few other comments.


Guillaume POIRIER wrote:

> +Recall
> +from the previous section that the final picture size you
> +encode should be a multiple of 16 (in both width and height). This can
> +be achieved by cropping, scaling, or a combination of both.

Random question: is there any particular reason for the linebreak after
the first word here? It's not actually important, since it'll disappear
in the *ML rendering, but it seems slightly odd.

> +  As you can see, rows and columns of the image naturally come in pairs.
> +  Thus your crop offsets and dimensions <emphasis>must</emphasis> be
> +  even numbers.
> +  If they are not, the chroma will no longer line up correctly with the
> +  luma.
> +  In theory, it's possible to crop with odd offsets, but it requires
> +  resampling the chroma which is potentially a lossy operation and not
> +  supported by the crop filter.

Similarly though less strangely here, the line breaks will disappear; I
wouldn't bother mentioning it anyway, since it looks to be an
(unnecessary but unobjectionable) extension into the XML docs of the
man-page technical requirement that sentences begin on new lines, except
that - as in the place quoted above - there are other places where new
sentences begin without corresponding line breaks.

> +  Then, test the values you get with <application>MPlayer</application>,
> +  using the command line <option>cropdetect</option> printed, and
> +  adjust the rectangle as needed.

I'd suggest "using the command line which was printed by
<option>cropdetect</option>", in order to reduce awkwardness.

> +  As stated earlier, when cropping, you'll want to increase the y-offset by
>    half the difference of the old and the new height so that the resulting
>    video is taken from the center of the frame. And because of the way DVD
>    video is sampled, make sure the offset is an even number. (In fact, as a

As a mostly unrelated note, I'd recommend the form "Y offset" in
instances such as this; it doesn't have to be done simultaneously, but I
think it works better.

-- 
       The Wanderer

Warning: Simply because I argue an issue does not mean I agree with any
side of it.

A government exists to serve its citizens, not to control them.